1. Field of the Invention
The present invention generally relates to a surveying method and a surveying instrument. The invention also relates to a computer program product causing the surveying instrument to perform the surveying method. In particular, the present invention relates to those surveying instruments and methods for performing photogrammetry, i.e. obtaining three-dimensional data of objects from plural images recorded from different positions.
2. Brief Description of Related Art
A conventional photogrammetric method uses a camera for obtaining two images of a scenery from two different locations. A surveying instrument which is separate from the camera and allowing to measure angles and distances is located spaced apart from the two locations of the camera, for determining the relative positions of the two locations from which the two images are taken. From an analysis of the two images and based on the information of the relative position of the two camera locations it is possible to obtain three-dimensional data of objects contained in the scenery.
A further conventional photogrammetric method in which two images of a scenery are obtained from different locations uses plural targets having predetermined distances from each other disposed in the scenery. The predetermined targets can be located in the obtained images and allow a determination and corrects scaling of three-dimensional data of other objects contained in the scenery.
The necessity of determining the two camera locations with a separate instrument located at a suitable distance from both camera locations or the necessity of locating predetermined targets within the scenery is burdensome, and also a source of measurement errors.